CAUSES OF ABORTION, STILLBIRTH, AND PERINATAL DEATH IN HORSES - 3,527CASES (1986-1991)

Pathology case records of 3,514 aborted fetuses, stillborn foals, or f oals that died < 24 hours after birth and of 13 placentas from mares w hose foals were weak or unthrifty at birth were reviewed to determine the cause of abortion, death, or illness. Fetoplacental infection caus ed by bacteria (n = 628), equine herpesvirus (143), fungi (61), or pla centitis (351), in which an etiologic agent could not be defined, was the most common diagnosis. Complications of birth, including neonatal asphyxia, dystocia, or trauma, were the second most common cause of mo rtality and were diagnosed in 19% of the cases (679). Other common dia gnoses were placental edema or premature separation of placenta (249), development of twins (221), contracted foal syndrome (188), other con genital anomalies (160), and umbilical cord abnormalities (121). Less common conditions were placental villous atrophy or body pregnancy (81 ), fetal diarrhea syndrome (34), and neoplasms or miscellaneous condit ions (26). A diagnosis was not established in 16% of the cases seen (5 85). The study revealed that leptospirosis (78) was an important cause of bacterial abortion in mares, and that infection by a nocardioform actinomycete (45) was an important cause of chronic placentitis.